Of course it's not necessary, it's a fashion. Choosing to make a TUI instead of a GUI is a fashion statement, it signals aesthetic alignment with nerdy shit and says the program isn't meant for common proles. There's pretty much nothing a TUI can do that a GUI can't do, while the opposite is very much not the case.

See also all the programmer blogs that feel the need to use a monospaced font for prose, to signal that they're a programmer.